Many printers, such as inkjet printers, operate by precisely ejecting microscopic drops of one or more substances from closely spaced nozzles of a printhead onto corresponding desired locations on a medium. The quality of the printed output resulting on the medium is dependent on proper operation of the printhead nozzles. For example, a nozzle may fail to eject drops at all. In another example, the nozzle may eject drops, but not along its intended trajectory, and as a result such drops get misplaced on the medium. These and other types of defective nozzle operations can unacceptably degrade the overall operation of the printer.